In general, an integrated circuit refers to an electrical circuit contained on a single monolithic chip containing active and passive circuit elements. Integrated circuits are fabricated by diffusing and depositing successive layers of various materials in a preselected pattern on a substrate. The materials can include semiconductive materials such as silicon, conductive materials such as metals, and low dielectric materials such as silicon dioxide. The semiconductive materials contained in integrated circuit chips are used to form almost all of the ordinary electronic circuit elements, such as resistors, capacitors, diodes, and transistors.
Typically, the substrate that is used to form integrated circuit chips is made from a thin slice or wafer of silicon. During production of integrated circuit chips, the semiconductor wafers are typically kept in carriers called cassettes. The wafers are separated from one another in the cassettes in a stacked arrangement. The wafers are transported in and out of the cassettes individually using wafer handling devices, which are also known as endeffectors. The endeffectors may be attached to a robot arm which moves the endeffectors in one, two or three directions.
The endeffectors are designed to enter the cassette in between a pair of adjacent wafers and to pick up one of the wafers for transfer into, for instance, a processing chamber. In the processing chamber, the semiconductor wafer is subjected to one of various processes. For instance, in the processing chamber, a chemical vapor deposition process, an etching process, an annealing process, and/or an epitaxial growth process may occur.
During the transport of wafers, care must be taken to ensure that the wafers are not damaged or contaminated. Thus, there have been many efforts in the industry to design endeffectors and robot arms that are capable of carefully transporting wafers in a very precise manner. Although many improvements have been made in the area of wafer handling, however, further improvements are still needed. For example, many wafer handling tools are relatively large and bulky in order to accommodate many of the instruments that are now attached to the tools in order to more precisely transport wafers. The size of the endeffectors, however, limit the speed at which the endeffectors are transported and accelerated. Further, relatively large endeffectors require that the processing chamber contain relatively large openings for receiving the endeffectors and the wafers carried thereon.
In view of the above, a need currently exists for further improvements in the design of endeffectors and robot arms. Further, a need exists for a relatively slim product design that not only ensures accurate wafer control but that can integrate a wafer detection system and a wafer pushing mechanism that may be used to grip wafers during transportation. A need further exists for a relatively slim endeffector design that may be used when handling cold wafers or when handling hot wafers.